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package main
import (
"encoding/json"
"errors"
"fmt"
"io"
"log/slog"
"net/http"
"regexp"
"github.com/TecharoHQ/anubis/cmd/anubis/internal/config"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
)
var (
policyApplications = promauto.NewCounterVec(prometheus.CounterOpts{
Name: "anubis_policy_results",
Help: "The results of each policy rule",
}, []string{"rule", "action"})
)
type ParsedConfig struct {
orig config.Config
Bots []Bot
DNSBL bool
}
type Bot struct {
Name string
UserAgent *regexp.Regexp
Path *regexp.Regexp
Action config.Rule
Challenge *config.ChallengeRules
}
func (b Bot) Hash() (string, error) {
var pathRex string
if b.Path != nil {
pathRex = b.Path.String()
}
var userAgentRex string
if b.UserAgent != nil {
userAgentRex = b.UserAgent.String()
}
return sha256sum(fmt.Sprintf("%s::%s::%s", b.Name, pathRex, userAgentRex))
}
func parseConfig(fin io.Reader, fname string, defaultDifficulty int) (*ParsedConfig, error) {
var c config.Config
if err := json.NewDecoder(fin).Decode(&c); err != nil {
return nil, fmt.Errorf("can't parse policy config JSON %s: %w", fname, err)
}
if err := c.Valid(); err != nil {
return nil, err
}
var err error
result := &ParsedConfig{
orig: c,
}
for _, b := range c.Bots {
if berr := b.Valid(); berr != nil {
err = errors.Join(err, berr)
continue
}
var botParseErr error
parsedBot := Bot{
Name: b.Name,
Action: b.Action,
}
if b.UserAgentRegex != nil {
userAgent, err := regexp.Compile(*b.UserAgentRegex)
if err != nil {
botParseErr = errors.Join(botParseErr, fmt.Errorf("while compiling user agent regexp: %w", err))
continue
} else {
parsedBot.UserAgent = userAgent
}
}
if b.PathRegex != nil {
path, err := regexp.Compile(*b.PathRegex)
if err != nil {
botParseErr = errors.Join(botParseErr, fmt.Errorf("while compiling path regexp: %w", err))
continue
} else {
parsedBot.Path = path
}
}
if b.Challenge == nil {
parsedBot.Challenge = &config.ChallengeRules{
Difficulty: defaultDifficulty,
ReportAs: defaultDifficulty,
Algorithm: config.AlgorithmFast,
}
} else {
parsedBot.Challenge = b.Challenge
if parsedBot.Challenge.Algorithm == config.AlgorithmUnknown {
parsedBot.Challenge.Algorithm = config.AlgorithmFast
}
}
result.Bots = append(result.Bots, parsedBot)
}
if err != nil {
return nil, fmt.Errorf("errors validating policy config JSON %s: %w", fname, err)
}
result.DNSBL = c.DNSBL
return result, nil
}
type CheckResult struct {
Name string
Rule config.Rule
}
func (cr CheckResult) LogValue() slog.Value {
return slog.GroupValue(
slog.String("name", cr.Name),
slog.String("rule", string(cr.Rule)))
}
func cr(name string, rule config.Rule) CheckResult {
return CheckResult{
Name: name,
Rule: rule,
}
}
// Check evaluates the list of rules, and returns the result
func (s *Server) check(r *http.Request) (CheckResult, *Bot) {
for _, b := range s.policy.Bots {
if b.UserAgent != nil {
if b.UserAgent.MatchString(r.UserAgent()) {
return cr("bot/"+b.Name, b.Action), &b
}
}
if b.Path != nil {
if b.Path.MatchString(r.URL.Path) {
return cr("bot/"+b.Name, b.Action), &b
}
}
}
return cr("default/allow", config.RuleAllow), &Bot{
Challenge: &config.ChallengeRules{
Difficulty: defaultDifficulty,
ReportAs: defaultDifficulty,
Algorithm: config.AlgorithmFast,
},
}
}
|
